# Epidemiology Ii

Topics: Odds ratio, Odds Pages: 3 (672 words) Published: August 21, 2013
1. HYPOTHESES

a. Main causal contrast of the theory

The frequency of Alzheimer’s disease in persons exposed to high sugar consumption is greater than frequency of Alzheimer’ disease in persons exposed to high sugar consumption if they had not been exposed.

b. Hypotheses in operationalized form

HYPOTHESIS 1: High sugar intake (E) causes Alzheimer’s disease (D) beyond chance. (Main Effect and its magnitude) HYPOTHESIS 2: Chronic stress is an alternative explanation for the association between high sugar intake and Alzheimer's disease. (Confounding) HYPOTHESIS 3: High sugar intake leads to diabetes, a major contributor to Alzheimer’s disease. (Mediation) HYPOTHESIS 4: The relationship between high sugar intake and Alzheimer's disease is particularly apparent among those with a family history of Alzheimer's disease. (Effect Modification)

c. DAG

d. Causal pies for main effect: Where X is unknown.

e. Response types for main effect
Type 1 – Doomed; Type 2 – Causal

f. Results that would be consistent with each hypothesis

HYPOTHESIS 1:
HYPOTHESIS 2:
HYPOTHESIS 3:
HYPOTHESIS 4:

2. TRUTH (DR. MEDITATIVE'S "STUDY") DATA IN TABLE 1

a. Test of each hypothesis: ANALYSIS FOR HYPOTHESIS 1: Testing for Association
| Alzheimer's disease (D+)| No Alzheimer's disease (D-)| High Sugar Intake (E+)| 56,312 + 33,456 =89,768| 428,431 + 80,249 =508,680| No High Sugar Intake (E-)| 9,355 + 13,386 =22741| 124,298 + 251,926 =376,224|

= [(89,768)(376,224)]/[508,680)(22,741)] ≈ 2.92

Find the Confidence Interval:

Step 1. Variance for the natural log of the OR:
1/a + 1/b + 1/c + 1/d = (1/89,768) + (1/508,680) + (1/22,741) + (1/376,224) =
0.0000597371305904

Step 2....